IRS probe ignored most influential groups

The tax agency has admitted to inappropriately scrutinizing tea party organizations that applied for tax-exempt status. But the IRS largely maintained a hands-off policy with the much larger organizations on the left and right that were most influential in the 2012 elections

Karl Rove's Crossroads GPS and Priorities USA, made up of former Barack Obama campaign aides, spent tens of millions of dollars on TV ads and get-out-the-vote efforts. Yet those groups escaped investigations into whether they abused their tax status to help shield donor identities.

Advocates for disclosure worry that government regulators will be less likely to scrutinize the more powerful groups going forward for fear they will appear to be targeting groups for political reasons.